[Elecraft] K3S - Is there a way to send CW via USB computer and hear the sidetones?

[Jerry Moore]

I'm attending CW academy and having a blast. I like being able to use my key
and hear the sidetone during practice. 
I use HRD and DM780. It keys my rig and will SEND CW without issue but I
don't hear the sidetone. 
I'd like to be able to put the rig into test mode (so it doesn't go over the
air) and hear what I send via computer.
Is that possible? I've not found a setting for that.
Thanks in advance.
Jer

Jerry Moore
CDXA, INDEXA, SKCC, Fists
AE4PB, K3S - S.N. 010324
http://www.qrz.com/db/AE4PB
An Amateur is - Considerate, Loyal, Progressive, Friendly, Balanced, and
Patriotic.